In view of the importance of sealing properties, elastic bodies (e.g., rubber) are used for parts that slide while maintaining their sealing performance, for example, a gasket which is integrated with a syringe plunger and forms a seal between the plunger and barrel. Such elastic bodies, however, have a slight problem with the sliding properties (see Patent Literature 1). Thus, a sliding property improving agent (e.g., silicone oil) is applied to the sliding surface; however, a concern has been raised over the potential adverse effects of silicone oil on recently marketed bio-preparations. Meanwhile, gaskets which are not coated with any sliding property improving agents have poor sliding properties, and thus do not allow plungers to be smoothly pushed, causing them to pulsate during administration. Hence, some problems occur such as an inaccurate injection amount and infliction of pain on patients.
In order to simultaneously satisfy these conflicting requirements, that is, sealing properties and sliding properties, a technique of coating with a self-lubricating PTFE film is proposed (see Patent Literature 2). PTFE films, however, are generally expensive and increase the production cost of processed products. Thus, the range of applications of the films is limited. Also, products coated with PTFE films might not be reliable when they are used in applications in which sliding or the like motion is repeated and durability is thereby required. Another problem is that since PTFE is sensitive to radiation, it cannot be sterilized by radiation.
Consideration may also be given to the use in other applications where sliding properties are required in the presence of water. Specifically, water can be delivered without a loss by reducing the fluid resistance of the inner surface of a pre-filled syringe or of the inner surface of a pipe or tube for delivering water, or by making the contact angle with water large or greatly small. Also, drainage of water on wet roads and of snow on snowy roads can be improved by reducing the fluid resistance of the groove surface of tires, or by making the contact angle with water large or greatly small. This results in enhanced grip performance and improved hydroplaning performance, leading to better safety. In addition, less adhesion of wastes and dusts can be expected when the sliding resistance of the sidewall surfaces of tires or walls of buildings is reduced, or when their contact angle with water is increased.
Further advantageous effects can be expected, such as: less pressure loss when water, an aqueous solution or the like is delivered through a diaphragm such as a diaphragm pump or valve; easy sliding of skis or snowboards achieved by enhancing the sliding properties of the sliding surfaces thereof; better noticeability of road signs or signboards achieved by enhancing the sliding properties thereof to allow snow to slide easily on the surface; reduction in water resistance or drag on the outer peripheries of ships and therefore less adhesion of bacteria on the outer peripheries, achieved by reducing the sliding resistance of the outer peripheries or by increasing the contact angle with water; and reduction in water resistance or drag of swimsuits achieved by improving the sliding properties of the thread surfaces thereof.